linux-kernel - [PATCH -mm v6 06/13] pagemap: use walk->vma instead of calling find

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Date:	Fri,  1 Aug 2014 15:20:42 -0400
From:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Dave Hansen <dave.hansen@...el.com>,
	Hugh Dickins <hughd@...gle.com>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	Jerome Marchand <jmarchan@...hat.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Naoya Horiguchi <nao.horiguchi@...il.com>
Subject: [PATCH -mm v6 06/13] pagemap: use walk->vma instead of calling find_vma()

Page table walker has the information of the current vma in mm_walk, so
we don't have to call find_vma() in each pagemap_hugetlb_range() call.

NULL-vma check is omitted because we assume that we never run hugetlb_entry()
callback on the address without vma. And even if it were broken, null pointer
dereference would be detected, so we can get enough information for debugging.

Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 fs/proc/task_mmu.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git mmotm-2014-07-30-15-57.orig/fs/proc/task_mmu.c mmotm-2014-07-30-15-57/fs/proc/task_mmu.c
index 4baf34230191..e4c6cdb9647b 100644
--- mmotm-2014-07-30-15-57.orig/fs/proc/task_mmu.c
+++ mmotm-2014-07-30-15-57/fs/proc/task_mmu.c
@@ -1073,15 +1073,12 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
 				 struct mm_walk *walk)
 {
 	struct pagemapread *pm = walk->private;
-	struct vm_area_struct *vma;
+	struct vm_area_struct *vma = walk->vma;
 	int err = 0;
 	int flags2;
 	pagemap_entry_t pme;
 
-	vma = find_vma(walk->mm, addr);
-	WARN_ON_ONCE(!vma);
-
-	if (vma && (vma->vm_flags & VM_SOFTDIRTY))
+	if (vma->vm_flags & VM_SOFTDIRTY)
 		flags2 = __PM_SOFT_DIRTY;
 	else
 		flags2 = 0;
-- 
1.9.3

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